import java.io.*;
import java.util.*;

public class Main{
    public static void main(String[]args){
        Scanner cin = new Scanner(System.in);
        int n = cin.nextInt();
        cin.nextLine();
        String s = cin.nextLine();
        for(int i=0; i<s.length(); i++){
            //char ch = (char)((s.charAt(i)-'a'+n)%26+'a');
            //System.out.print(ch);
            System.out.print((char)((s.charAt(i)-'a'+n)%26+'a'));
        }
        System.out.println("");
        cin.close();
    }
}